It's amazing, what's the exact hashrate this rock pi do? 3 or 4 mhs?
And which model do you use?
I too use a RK3399 based RockPi. It's a ARM chip commonly used in set-top boxes.
In order to mine it does have to run 64-bit linux. Mine runs Ubuntu 18.04 LTS server (+ Mint GUI for demonstration of the Verus-Desktop GUI wallet). Mining on 6 cores (4x A53 + 2x A72) it does about 2.5-3.0 MHs on Verushash 2.2 at 9 Watts indeed.
It may not be a huge hashrate, but's above average on MH/W
Mining on an Android TV is a unknown to me. Lots of different processors used and very little Android miners available.